1. Field of the Invention
The invention relates to dermatologically acceptable pressure sensitive tape containing uniformly dispersed within the adhesive mass an effective, releasable concentration of tretinoin (all trans-retinoic acid, or Vitamin A acid). More particularly, it relates to an adhesive tape comprising a flexible backing having a dermatologically acceptable pressure sensitive adhesive mass coated on one side of said backing, this adhesive mass being compatible with, and containing uniformly distributed therethrough, a therapeutically effective concentration of tretinoin. This product is particularly advantageous for treating such dermatological disorders as warts and localized episodes of acne vulgaris.
2. Description of the Prior Art
It has been demonstrated that prolonged topical application of Tretinoin (Vitamin A acid) is effective in the treatment of acne (Kligman, A. M., "Topical Vitamin A acid in Acne Vulgaris", Arch Derm., 99: 469-476 April 1969). Kligman utilizes a composition in which Vitamin A acid is dispersed in a water-miscible (substantially oil- and fat-free) liquid carrier having high solvating action. The topical application of this Vitamin A acid composition causes irritation of the skin in the treated areas. See U.S. Pat. No. 3,729,568 issued Apr. 24, 1973, to Albert M. Kligman. It has also been reported that tretinoin is effective in the topical treatment of such other skin conditions as warts. (Lester, R. et al.: Arch Derm. 104: 330, 1971).
It has also been found that tretinoin can be supplied in effective topical doses from cream or gel formulations containing suitable concentrations of tretinoin. A cream formulation is generally more acceptable to patients than the liquid vehicle from the point of view of aesthetics and ease of application. Moreover, another important advantage of the cream form of tretinoin is that it reduces the side effects normally associated with the topical application of tretinoin. These side effects, erythema, stinging and itching, may be sufficient to cause the patient to discontinue the application of tretinoin before it can be fully effective upon the condition being treated.
Notwithstanding these advantages, cream formulations containing tretinoin possess some undesirable attributes. One of these undesirable attributes is the difficulty in uniformly applying sufficient amounts of the active ingredient to the lesion being treated to be effective and at the same time avoid local excesses, surface spread or pooling into facial creases, the nasolabial folds and corners of the mouth where the cream may cause erythema, stinging and itching. Another undesirable attribute of cream formulations of tretinoin is their relative instability, often necessitating the use of refrigeration or antimicrobial preservatives to prevent microbiological contamination, as well as special additives to maintain physical stability. One way of overcoming some or all of these undesirable attributes is by using gel formulations.
Occlusive dressings have been found to promote penetration of tretinoin through the skin. Occlusion also tends to keep warts moist, and prior wart treatments have been found to be more effective on wet warts than on dry warts.
U.S. Pat. No. 3,632,740, issued Jan. 4, 1972, discloses uniformly dispersing a topical corticosteroid in the pressure-sensitive adhesive coating of an adhesive tape for use in topical steroid therapy.